SEGMENTED WORMS— THE ANNELIDS 



171 



gravel for the same purpose. Once properly ground, the food is then 

 passed to the intestine where enzymes are poured on it from the intestinal 

 wall. Digested food is then absorbed by the blood vessels, which liber- 

 ally supply the intestine, and is thus carried to all parts of the body. 

 The indigestible part is expelled through the anus. 



The area where absorption of food can take place is increased because 

 the intestine folds downward from the dorsal surface to form a projection 



Brain 



Pharynx 

 Septum 



Hearts 



Oesophagus 

 Seminal vesicle 



—Seminal receptacle 

 Testes 



Vas aeterens 



Ovary 



Oviduct 



Crop 



Dorsal blood vessel 



Nephndium 



Gizzard 



Fig. 12.1. Dorsal view of the internal organs found in the anterior region of the earth- 

 worm. The nephridia are shown in only one segment ; actually they are found in each 

 segment. The seminal vesicles, including the testes and vas deferens, have been re- 

 moved on the right side to show the organs beneath. 



